LS Dyna Tutorial FEA
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Drop Test Tutorial
Example Plate impacting Plate1DefinitionA Shell Elements drop and rebounds from a elastic plate.Plate measure 40*40*1 mm3 (16 elements)Dropped shell has 10mm side length and 2 mm thickness.Drop height is 10mmElement formulation is Belutschko-TsayDefine a surface to surface contact with 2 way detection.Define the elastic plate as Master and impacting shell as slave.Initial Velocity is 100,000 mm/sec verticallyEnd Time is 0.0002 sec.2Set-UpFor model setup we use various option in the preprocessor tab.Create 2 areas with required dimension as shown below (Preprocessor-Modeling-create-).Transform drop shell to required drop height.
3MeshingPartMaterialElement TypeReal constant11112112
Define Element Type 163 (Preprocessor-Element type-add/edit/delete-)Part should be defined using right combination of material , real contact , element type. Before meshing this has set and can be confirmed at status bar.
Status Bar4Meshing contDefine Real Constant to assign section properties or thicknesses. For each thickness there should be one real constant. (Preprocessor-Real Constants)
5Meshing ContMaterial PropertiesDefine material properties for various parts using option shown below. (Preprocessor-Material Props-Material Models)
6Creating PartsAssign the correct material, section properties and element type to create parts.For LS-Dyna to recognize a part, its should be a group of elements that have the same combination of element type, real constant set, and material reference numbersRepeat this to all area/components (Preprocessor-Meshing Mesh Attributes)
7Revisiting MeshingSet line seeding or element size. (Preprocessor-Meshing-Mesh tool-Set)Mesh Volume ,Areas and lines to generate solid, shell or beam elements.Refer images below to access the meshing tool.
8Creating ComponentsWe need to create node and elements components for Adding Constrains to a group of nodesDefining Velocity to a part (part nodes need to be grouped)Defining a master surface and node surface (associated nodes of surface need to be grouped)To request output for required parts/region of interest.In this model create node and element component for both the areas you could name them for example as plate_e and plate_n for element and node components. Refer images below to access the menu options.
9Adding Constrains to ModelThe plate is fixed at its boundaries (Preprocessor-LS-DYNA-Constraints-On Nodes)Create a node component or select the desired nodes to apply the constrains.Refer images below to access the menu options to add constrain.
10Defining contactsIn this model we will create a Automatic Surface to Surface Contact. Choose the moving plate as contact surface and fixed plate as target surface. (Preprocessor-LS-DYNA-Contact-DefineContact)
11Initial VelocityThe moving plate has initial velocity of 100,000 mm/s in vertical direction.Initial velocity can be applied using option under LS-Dyna Option tab as show below. (Preprocessor-LS-DYNA-Initial Velocity-w/Nodal Rotate)
12Solution SettingAs per problem definition end time is 0.0002 sec, remember that most of impact problem occur over a time of ms.We now use option in the solution tab (Solution Time Controls Solution Time)
13Output ControlsIn output controls weRequest for both Ansys and LS-Dyna Result formatsSet the frequency at which result files are writtenRequest for Special Ascii files which has information on system energies, Nodal and Elemental results.Select the components for which Time-History results has to be written.
You could request for 10 Ascii files at a time the most frequent used are Global statistics dataBoundary condition forces and energyMaterial energies summaryGeometry contact entitiesNode data
14Solution and ResultsClick on the Solve option in run the simulation (Solution Solve)
As Discussed before this example Post processing option areGeneral Post Proc Time History Post ProAttached is the animation of the solved problem.Utility Menu > PlotCtrls > Animate > Over Results
15Time- History Post ProcessingTimeHist Postpro > Variable Viewer > File > Open > Explicit Dynamics Results (*.his) > Jobname.his